1. Patients who have received treatment with an experimental agent within the last 30 days prior to Visit 1 (Screening). Patients who have completed previous milnacipran studies (ie, all respective protocol-related study procedures have been completed by the patient) are eligible to participate. Any patients who failed screening in previous milnacipran studies may be re-evaluated, and eligible patients may enroll. Patients currently enrolled in Study MLN-MD-06 are not eligible to participate